Well, you have been getting advice that conflicts with what we have learned here over the years. You say you want to do everything right. Here are the lessons learned from years of reading Internet gardening forums. 1. NEVER rototill in preparation for laying seed or sod. 2. You can sod any day of the year. 3. Palmetto is a relatively poor variety. Floratam is the one you really want. So that bad news is that you wasted time and money preparing the soil. The good news is you can still have the best looking lawn in the neighborhood starting from where you are. Before the sod arrives, go out and water the soil completely. Water for at least an hour. This will settle the soil that is currently fluffy. After the soil settles some, level it again using a rake or filling in with sand/soil. Try not to raise the surface of the soil by blanket top dressing. All you want to do is fill the holes. Then water it again to settle the new surface. You can get the most level surface by dragging a piece of weighted chain link fence over the soil. That tool will loosen the high spots and drag high soil into the low spots that you cannot see. Then after your sod goes down, rent a water fillable roller to push the sod down to the surface of the soil. Roots from the sod will not grow through the air to reach the soil. The sod has to be touching everywhere. Since you cannot afford a sprinkler, go to Home Depot and get a Vigoro water hose timer. Then get as many oscillating sprinklers as you need to cover your lawn all at the same time. Then go to Sears and get Craftsman brand hoses to connect to the timer and the sprinklers (Sears' hoses do not leak at the fittings if you tighten them properly). You might need splitters to feed all the hoses out of the timer. I like the big green and black ones from Lowe's. Set your timer to go off every day, morning, noon, and night, for 10 minutes each time. You need to do this so the sod will knit to the underlying soil. If you do this for three weeks, the roots will be in and you're off to the races. After the roots are in you can back off on the watering. Ultimately you want to back off to watering once every week in the summer heat and once or twice a month the rest of the year. Use your timer to do this. I was going to lose my lawn this year until I got the timer rigged up. Mulch mow St Augustine at the mower's highest setting. Weld the adjusters in place so that your well meaning brother in law doesn't come by some day to do you a favor and he scalps your nice lawn. St Aug never needs to be scalped. Just mowing at the highest setting will give you the best looking lawn in the neighborhood. I fertilize with organic fertilizer 5 times per year on the federal holidays. I start on Washington's Birthday and end on Thanksgiving. If you use synthetic you can follow the same schedule except skip 4th of July...and also don't do the first one until after you have mowed real grass for the second time in the spring. If you don't want to spend the money on new hoses, cut the male ends of your current hoses off and replace them with the black plastic repair ends from Lowe's. The stamped brass fittings are the worst. The Sears brass fittings are slightly better. I really prefer the black plastic male fittings for all my hoses. They seal tight every time.

You could do 50/50 of soybean meal and alfalfa pellets (not meal) at the rate of 30lbs per 1000 sqft to feed the microherd in the soil. You will have to spread each separately with rotary spreader. Use the highest setting for alfalfa pellets and probably halfway between highest and lowest for soybean meal. Do you have ortho-dial? You could get unsulfured blackstrap molasses and APPLE VINEGAR (not the fake one). again 50/50 at the rate of 4oz per 1000 sqft after you've spread soybean meal and alfalfa pellets. Mow at the highest setting. Water deeply whenever large area are wilting. Try to go as long as you can between watering.

On a cloudy morning take another picture or two. Get down so you're camera lens is 3 inches away from the grass blades and take a picture of the blades where they are turning from green to brown. I strongly suspect the grass was flooded and you have a disease. Some diseases can be treated with ordinary corn meal. I suspect yours is caused by flooding and will require a chemical fungicide. Post the new pictures and we can tell more. New Orleans, with highs in the low 90s, is more humid than hot. While it might be the most uncomfortable place in the US, the grass doesn't see it that way. Phoenix, at 115 degrees, is hot. The big difference is you don't get nearly enough evaporation in NO to justify watering so much to saturate the soil. All that you needed was to keep the surface of the underlying soil moist so the roots would grow down into it. Watering 3x per day, 5 minutes at a time, for a total of 15 minutes per day would have been more in the ballpark. Is there any chance the place you took the picture of is a low spot where there is standing water? Once the sod is knit to the ground, you can back way off on the frequency and go deeper. Here is a lot more on watering for mature grass. Watering: Deep and infrequent is the mantra for watering. This is for all turf grass all over the place. Deep means 1 inch all at one time. Put some cat food or tuna cans around the yard, and time how long it takes your sprinkler(s) to fill all the cans. Memorize that time. That will be the time you water from now on. My hose, sprinkler and water pressure takes 8 full hours to fill the cans. Your time will likely be less. I like gentle watering. As for watering frequency, that depends on the daytime air temperature. With temps in the 90s, deep water once per week. With temps in the 80s, deep water once every 2 weeks. With temps in the 70s, deep water once every 3 weeks. With temps below 70, deep water once a month. Note that you have to keep up with quickly changing temps in the spring and fall. This deep and infrequent schedule works in Phoenix and in Vermont, so it should work for you. The reason for deep and infrequent is to grow deeper, more drought resistant roots and to allow the soil to dry completely at the surface for several days before watering again. If it rains, reset your calendar to account for the rainfall. With new bermuda or St Augustine sod, you can start treating it like mature turf much sooner than they do with the grasses in the north. I would transition as quickly as possible to watering 1/2 inch every 3-4 days until the temps drop back into the mid to low 80s. Then go to 1/2 inch per week and see if you can go to 1 inch all at once every 2 weeks.

Looks like it to me. Here is a link to some more information, which you might have already found. I would assume the grass came with the disease which got much worse with the rain. Take a note and don't buy grass from that supplier again. Being an organic kind of guy, I would be hitting the grass with ordinary corn meal at 15 pounds per 1,000 square feet every 3-4 weeks for the rest of the summer. This is INSTEAD of using a fungicide. As discussed in the link above, this is a soil borne disease. These problems are caused by an imbalance of beneficial versus pathogenic microbes - essentially an unhealthy soil. The fastest way to restore the soil to health is to use organic fertilizer, NOT fungicide. Corn meal has the additional benefit of heavily populating the soil with a predatory, but beneficial fungus called Trichoderma (try koh DER mah). Not all fungi cause disease. If you cannot find ordinary corn meal at your local feed stores (call first), then cracked corn will work. If you cannot find either one, then look for a grocery store catering to the Hispanic market. They will have 25-pound bags of corn flour. They will also have 25-pound bags of tortilla ready-mix which has baking soda and baking powder in it. The bags are almost identical, but you want the plain corn flour. Ask for help if you cannot tell them apart. If you have any doubts about the effectiveness of organic fertilizer, please ask. I think you ran into an unfortunate weather situation - unlucky timing. The grass could have been afflicted before you bought it, but that's hard to prove. It may have a guarantee or you might get a discount on buying again from the same supplier.